Murine arylsulfatase B is subject to regulation by Asr-1, a genetic element closely linked to As-1, the putative structural locus for arylsulfatase B. Asr-1 promotes accumulation of arylsulfatase B molecules determined by the As-1 allele on the same chromosome (cis-dominant regulation). Asr-1 and at least one additional genetic element influence the numbers of arylsulfatase B molecules in murine liver. Murine arylsulfatase B will be purified to homogeneity using a combination of traditional methods and two affinity steps. The purified arylsulfatase B will be used to raise specific antibody. Immunoaffinity columns will be prepared and used to isolate arylsulfatase B from kidney and liver of SWR/J, C57BL/6J, and A/J mice. The purified enzymes will be biochemically characterized, including peptide analysis, to search for possible amino acid differences. Methods will be developed for estimation of incorporation of label into arylsulfatase B, and these will be adapted to studies of enzyme synthesis and clearance. Relationships between anionic (arylsulfatase B') and cationic arylsulfatase B isozymes will be investigated by studying their covariation in brain tissue of selected inbred strains and progeny of appropriate crosses and by structural analysis following their immunopurification. A pulse/chase labelling system will be developed to study a possible precursor-product relationship between these isozymes.